You are not using a standards compliant browser. Because of this you may notice minor glitches in the rendering of this page. Please upgrade to a compliant browser for optimal viewing:
FirefoxInternet Explorer 7Safari (Mac and PC)

When You're Visited By A Copy Of Yourself, Stay CalmYou're born, live and die with one body. One is all you get. But some people, says neurologist Oliver Sacks, occasionally get another one; it's an illusion, a hallucination, but it follows you around, copying everything you do. It looks like it's keeping you company. But it's not.